NSE Derivative Lot Size Changes: What You Need to Know From December

As the year-end expiry approaches, NSE’s revised market lot sizes for major index derivatives, announced on 3 October 2025, are set to take effect soon.

With 18 December marking the final phase under existing lot sizes, it is important to understand when the new lots apply and how they will impact position sizing and risk management in 2026.

What Has Changed in Index Derivative Lot Sizes?

The National Stock Exchange has revised the market lot sizes for several key index derivative contracts in line with periodic reviews mandated by SEBI.

Updated Lot Sizes for Index Derivatives

Index	Symbol	Existing Lot Size	Revised Lot Size
Nifty 50	NIFTY	75	65
Bank Nifty	BANKNIFTY	35	30
Nifty Financial Services	FINNIFTY	65	60
Nifty Mid Select	MIDCPNIFTY	140	120

The Nifty Next 50 (NIFTYNXT50) contract continues with the same lot size of 25, with no change announced.

What Matters Right Now

As of 18 December, traders are in a transition phase:

• All weekly and monthly contracts expiring up to December 30, 2025 will continue to trade with the existing lot sizes
• Contracts expiring from January 2026 onward will reflect the revised lot sizes
• All existing quarterly and half-yearly contracts, irrespective of their original introduction, will have their lot sizes revised after the December monthly expiry

In simple terms, December expiry is the dividing line between old and new lot structures.

Why NSE Revises Lot Sizes

Lot sizes are reviewed periodically to ensure that the notional value of derivative contracts remains manageable as index levels change over time.

This helps:

• Keep contracts accessible for a wider set of traders
• Improve risk containment
• Prevent excessive capital concentration per lot
• Maintain market efficiency and liquidity

The revised lots bring down exposure per contract, especially in Bank Nifty and Midcap Nifty, where absolute contract values had grown significantly.

What This Means for Traders Going Forward

1. Lower Exposure per Contract

With smaller lot sizes, each contract now represents slightly lower market exposure, which can be helpful for risk-controlled trading.

2. Changes in Position Sizing

If you trade fixed quantities (for example, 2–3 lots), your overall exposure and payoff profile will change from January onwards.

3. Option Selling & Hedging Adjustments

Option sellers should reassess:

• Hedge ratios
• Quantity-based risk limits
• Margin deployment

Even a small lot size reduction can impact payoff symmetry and breakeven levels.

4. Spread Traders: Take Note

Certain day spread order books will not be available for specific contract combinations around the transition period, which is relevant for traders running calendar or spread strategies

What Traders Should Do Before December Expiry

With the change now close at hand, traders should:

• Review any open quarterly or long-dated positions
• Clearly differentiate December expiry contracts vs January contracts
• Check broker platforms for updated lot sizes and margin requirements
• Avoid quantity mismatches while rolling over positions